Segmental abrasive wheel



Dec. 13, 1966 H. J. JEFFERS 3,290,835

SEGMENTAL ABRASIVE WHEEL Filed July 28, 1964 INVENTOR.

HENRY J. JEFFERS FIG. 4

A'I 'TORNEY United States Patent "ice 3,290,835 SEGMENTAL ABRASIVE WHEELHenry J. Jeffers, Lewiston, N.Y., assignor to The Carborundum Company,Niagara Falls, N.Y., a corporation of Delaware Filed July 28, 1964, Ser.No. 385,639 9 Claims. (Cl. 51-209) The invention of the presentapplication relates to segmental abrasive wheels and is particularlyconcerned with such wheels in which the segmentscomprise diamondabrasive.

It is an object of the present invention to provide abrasive wheels ofthe character described in which diamond abrasive segments bonded withmetal or the like are embedded in an organic-bonded mass of softerabrasive gram.

Another object of the invention is to provide abrasive wheels of thecharacter described in which mounting means for said wheels are alsoembedded in an organicbonded mass of relatively soft abrasive grain.

A further object of the invention is to provide abrasive Wheels of thecharacter described in which there are a plurality of series of diamondabrasive segments.

Still another object of the invention is to provide abrasive wheels ofthe character described which cut more smoothly and with reducedvibration.

Other objects and advantages of the present invention will be apparentfrom the following description taken in conjunction with theaccompanying drawings in which:

FIGURE 1 is a plan view of an abrasive disc wheel embodying the presentinvention;

FIGURE 2 is a transverse sectional view on line 22 of the abrasive discwheel shown in FIGURE 1;

FIGURE 3 is a transverse sectional view on line 33 of the abrasive discwheel shown in FIGURE 1; and

FIGURE 4 is an inverted perspective view of a diamond abrasive segmentsuch as is employed in producing abrasive wheels according to thepresent invention.

Referring to FIGURES 1-3, inclusive, the abrasive disc wheel referred tocomprehensively by the reference numeral 11 is seen to comprise anabrasive body portion 13 of substantial thickness in one face of whichthere are embedded a plurality of abrasive segments 15, 16 each of whichis suitably secured to a mounting plate 18. In the other face of thebody portion 13 of the wheel 11 there are embedded a plurality ofwheel-mounting nuts 20, 21.

Abrasive wheels according to the invention may be easily manufacturedand readily mounted for use. The production of such a Wheel may beaccomplished as follows:

EXAMPLE I A series of alternating diamond abrasive segments 15 and 16 isplaced in a ring mold (not shown). The outer abrasive faces of thesegments are turned down to rest on the bottom mold plate. The latter isupwardly beveled adjacent its outer edge so that the outer abrasivefaces of the segments 15 are arranged at an obtuse angle with respect tothe outer abrasive faces of the segments 16. An abrasive mix, preferablyone with a resinoid bond, is then placed in the mold around the segments15 and 16, and leveled off. An annular top mold plate, to the undersideof which the wheel-mounting nuts 20 and 21 have been secured by machinescrews passing through the plate and engaging in the threaded bores 22and 23, respectively, of the nuts, is then placed on the mix and apressure of about 210 kg./cm. is applied to consolidate the mix, thusmolding the nuts 20 and 21 in the abrasive body portion 13 of the wheel.The mold barrel and bottom mold plate are then removed and the wheel isturned over and cured with the top mold plate still attached. Uponcompletion of the cure the machine screws 3,290,835 Patented Dec. 13,1966 are removed and the wheel, with substantially fiush abrasivesegments, is ready for finishing and sale or use.

Novel segmental wheels according to the invention could, if desired, beformed in other ways according to known practices. However, theprocedure given in Example I is ordinarily preferred.

In carrying out the manufacture of the present novel segmental abrasivewheels the abrasive segments 15 and 16 are preferably metal or metalloidbonded and comprise about 5-10 percent of. diamonds. Segments producedaccording to the following example are very effective.

EXAMPLE II A mix consisting of the following:

Percent Wolfram carbide, finely divided 85.0 Cobalt, finely divided 8.5Diamond abrasive, 20-46 grit 6.5

is blended together and heated to about 1300 C. in a stop mold. Pressureis then applied to close the mold against the stop. After pressing, thesegments are cooled and attached to the mounting plates or spiders 18.

The mounting plates 18 for the segments are preferably steel and areU-shaped, with the legs 19 of the U being shorter than the base andextending divergently, and provided with irregular contours which permitfirm anchoring in the abrasive body portion 13 of the wheel. Thesegments 15 and 16 are secured to the outsides of the bases of theU-shaped plates. The mounting plates 18 can be cut to shape or may bepunched from perforated sheet metal. As shown, they preferably are aboutthe same width as the abrasive segments with the legs 19 extendingbeyond the segments. i

It will be understood that alternatively the abrasive segments may beformed of diamond abrasive and other hard bonds such as othercarbide-metal compositions, steel, and hard bronzes as well as hardceramic bonds. Many bonds of these types are well-known. It will also beunderstood that the percentage of diamond abrasive used in such segmentsmay vary as found desirable. The segments may be of any desired size.

Depending upon the material of the mounting plates 18 and the bond forthe diamond abrasive segments 15 and 16, the latter may be attached tothe former by any suitable means. The use of a suitable, conventionalsilver solder is preferred. However, strong, resinous adhesives such aspolyester or epoxy adhesives will be satisfactory in many instances andother adhesives may be used when desired.

The bond and abrasive of abrasive body portions 13 of segmental abrasivewheels according to the present invention are preferably softer thanthose of the abrasive segments 15 and 16 and will, therefore, wear awayat least as fast as the segments. Preferably the body portion is formedof resinoid-bonded abrasive particles, the abrasive being, for example,fused aluminum oxide or silicon carbide. Although the grit size of theabrasive used in the abrasive body portion is preferably finer than thatof the diamond abrasive in the segments 15 and 16 the proportions ofbond to abrasive, the exact bond composition, and the type of abrasiveare not critical and any known or desired abrasive mix may be used. Asexamples of usable mixes are those disclosed in US. Patents 2,076,517and 2,254,254, issued respectively on April 6, 1937 and September 2,1941.

The mounting nuts 20 and 21 embedded, substantially flush, in the backof the wheels 11 may be of any desired shape and size. As mentionedabove, they are provided with threaded bores 22 and 23, respectively,into which bolts may be threaded to hold the wheel on a metal base platefor rotation. Preferably the nuts Will be formed of steel to giveadequate strength to the mounting.

It will be understood that the precise arrangement of abrasive segmentsshown in the accompanying drawing is not critical. The segments may becloser together or further apart in either or both of the series and, ifdesired the number of segments in one series may be more or less thanthe number in the other. The number, spacing, and arrangement of theabrasive segments are matters of choice to be decided on the basis ofresults desired.

The same is true of the number and arrangement of mounting nuts. Inusing a segmental wheel of the present invention it is mounted on agrinding machine by securing it to a mounting plate with machine screwsthat pass through the plate and engage in the nuts 20 and 21. Enough ofsuch nuts should be provided to adequately secure the wheel.

Segmental abrasive wheels according to the invention are characterizedby high abrasive eificiency, long life, and convenience in use. Becauseof their novel construction they are lighter and easier to handle thanthe wheels previously used which included heavy base plates to which thesegments were secured by soldering, brazing, or the like. In additionthey cut more smoothly with reduced noise and vibration.

Parts and percentages referred to-herein are parts and percentages byweight.

I claim:

1. A segmental diamond abrasive wheel which comprises a disc-likeabrasive body portion comprising abrasive particles and an organic bondtherefor, said abrasive body portion having embedded in one face thereofa plurality of annularly-spaced diamond abrasive segments, the bond ofsaid segments being harder than the bond of said body portion, and saidabrasive body portion having embedded in the opposite face thereof aplurality of annularly-space mounting nuts, said segments being firmlysecured to individual mounting plates, each of said mounting platescomprising a plurality of portions extending beyond the periphery of thesegment mounted thereon and being wholly embedded in said body portionwhereby to permit firm anchoring of said segments in said abrasive bodyportion.

2. A segmental diamond abrasive wheel asset in claim 1 in which saidsegments are mounted on U-shaped plates that are embedded in said bodyportion and the outer faces of said segments are flush with the surfaceof said body portion.

3. A segmental diamond abrasive wheel as set forth in claim 2 in whichsaid organic bond is a resinoid.

4. A segmental diamond abrasive wheel as set forth in claim 2 in whichthe bond of said segments comprises a metal.

5. A segmental diamond abrasive wheel as set forth in claim 2 in whichthe abrasive of said body portion is softer than diamond.

6. A segmental diamond abrasive wheel as set forth in claim 2 in whichsaid segments are radially oriented in said body portion.

7. A segmental diamond abrasive wheel as set forth in claim 2 in whichsaid segments are mounted in two radially spaced series. I

8. A segmental diamond abrasive wheel as set forth in claim 7 in whichthe longitudinal axes of the segments of the outer one of said radiallyspaced series are inclined with respect to the longitudinal axes of thesegments of the inner series.

9. A segmental diamond abrasive wheel which comprises an annular,disc-like abrasive body comprising abrasive particles and a resinoidbond therefor, a plurality of diamond abrasive segments, the bond ofsaid segments comprising a metal and being harder than the bond of saidbody portion, each of said segments being mounted on U-shaped plateswhich are embedded in one face of said body portion with the outerabrasive face of said segments substantially flush with the surface ofsaid body portion, and a plurality of annularly-spaced mounting nutsembedded in the opposite face of said body portion with the outer facesof said nuts substantially flush with the surface of said body portion.

References Cited by the Examiner UNITED STATES PATENTS 3/1922 Gardner5l209 12/1940 Benner et al. 5l-209

1. A SEGMENTAL DIAMOND ABRASIVE WHEEL WHICH COMPRISES A DISC-LIKEABRASIVE BODY PORTION COMPRISING ABRASIVE PARTICLES AND AN ORGANIC BONDTHEREFOR, SAID ABRASIVE BODY PORTION HAVING EMBEDDED IN ONE FACE THEREOFA PLURALITY OF ANNULARLY-SPACED DIAMOND ABRASIVE SEGMENTS, THE BOND OFSAID SEGMENTS BEING HARDER THAN THE BOND OF SAID BODY PORTION, AND SAIDABRASIVE BODY PORTION HAVING EMBEDDED IN THE OPPOSITE FACE THEREOF APLURALITY OF ANNULARLY-SPACE MOUNTING NUTS, SAID SEGMENTS BEING FIRMLYSECURED TO INDIVIDUAL MOUNTING PLATES, EACH OF SAID MOUNTING PLATESCOMPRISING A PLURALITY OF PORTIONS EXTENDING BEYOND THE PERIPHERY OF THESEGMENT MOUNTED THEREON AND BEING WHOLLY EMBEDDED IN SAID BODY PORTIONWHEREBY TO PERMIT FIRM ANCHORING OF SAID SEGMENTS IN SAID ABRASIVE BODYPORTION.